Controlling of communication network comprising virtualized network functions

ABSTRACT

An apparatus and a method are configured to host subscription data of communication elements of a communication network attached to virtualized network functions on the basis of a stored indication, and storing an indication for the virtualized network functions indicating whether the virtualized network functions are de-instantiated. A message directed to a virtualized network function is received and processed, and the method then checks whether the virtualized network function is indicated to be still instantiated or not. If the results of the checking is that the virtualized network function is de-instantiated, a simulation process is conducted.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationSer. No. 15/112,039 filed on Jul. 15, 2016 which is a 371 Application ofInternational Patent Application No. PCT/EP2014/050910, filed Jan. 17,2014. The contents of these applications are hereby incorporated byreference.

FIELD

The present invention relates to apparatuses, methods, systems, computerprograms, computer program products and computer-readable media usablefor controlling a communication network comprising at least onevirtualized network function.

DESCRIPTION OF THE RELATED ART

The following description of background art may include insights,discoveries, understandings or disclosures, or associations, togetherwith disclosures not known to the relevant art prior, to at least someexamples of embodiments of the present invention but provided by theinvention. Some of such contributions of the invention may bespecifically pointed out below, whereas other of such contributions ofthe invention will be apparent from the related context.

The following meanings for the abbreviations used in this specificationapply:

-   3GPP 3^(rd) Generation Partner Project-   ATCA: advanced telecommunications computing architecture-   BGCF: breakout gateway control function-   BS: base station-   CAM cloud application manager (formerly known as CFW)-   CFW cloud framework-   CP control plane-   DP data plane-   CPU: central processing unit-   DL: downlink-   eNB: evolved node B-   EPC: evolved packet core-   ETSI European Telecommunications Standards Institute-   GGSN: gateway GPRS support node-   GO: global orchestrator-   GPRS General Packet Radio Service-   GTP-C GPRS tunnelling protocol-control plane-   GUMMEI: globally unique MME identifier-   GUTI: globally unique temporary identifier-   HSS: home subscriber server-   IBCF: interconnection border control function-   ID: identification, identifier-   IMS: IP multimedia system-   IP Internet protocol-   LTE: Long Term Evolution-   LTE-A: LTE Advanced-   MCC: mobile country code-   MGCF: media gateway control function-   MME mobility management entity-   MNC: mobile network code-   M-TMSI: MME temporary mobile subscriber identity-   NE network element-   NFV: network function virtualization-   NUC: network utilisation controller-   OAM operation administration maintenance-   OFC: open flow controller-   P-CSCF: proxy call session control function-   PGW packet data network gateway-   PGW-C PGW control plane-   PGW-U PGW user plane-   PIP/InP physical infrastructure provider/infrastructure provider-   RAN: radio access network-   SCTP: stream control transmission protocol-   SDN software defined networks/networking-   SGSN: serving GPRS support node-   SGW signaling gateway-   SGW-C SGW control plane-   SGW-U SGW user plane-   SIP: session initiation protocoll-   UE: user equipment-   UL: uplink-   UMTS: universal mobile telecommunication system-   UP user plane

Embodiments of the present invention are related to a communicationnetwork comprising at least one virtualized network function. Avirtualized network function may be of any type, such as a virtual corenetwork function, a virtual access network function, a virtual IMSelement, or the like.

SUMMARY

According to an example of an embodiment, there is provided, forexample, a method comprising determining that at least one virtualizednetwork function providing services related to a communication networkis to be de-instantiated, preparing an indication related to thede-instantiation of the at least one virtualized network function, andcausing transmission of the prepared indication to at least one of anetwork element of the communication network, a network function of thecommunication network and a database to which network elements ornetwork functions of the communication network have access.

Furthermore, according to an example of an embodiment, there isprovided, for example, an apparatus comprising at least one processor,and at least one memory for storing instructions to be executed by theprocessor, wherein the at least one memory and the instructions areconfigured to, with the at least one processor, cause the apparatus atleast: to determine that at least one virtualized network functionproviding services related to a communication network is to bede-instantiated, to prepare an indication related to thede-instantiation of the at least one virtualized network function, andto cause transmission of the prepared indication to at least one of anetwork element of the communication network, a network function of thecommunication network and a database to which network elements ornetwork functions of the communication network have access.

According to a further example of an embodiment, there is provided, forexample, a method comprising obtaining an indication related to ade-instantiation of at least one virtualized network function providingservices related to a communication network, and processing the obtainedindication for determining or recognizing the virtualized networkfunction being de-instantiated and for avoiding to conduct acommunication attempt to the virtualized network function to bede-instantiated.

Furthermore, according to an example of an embodiment, there isprovided, for example, an apparatus comprising at least one processor,and at least one memory for storing instructions to be executed by theprocessor, wherein the at least one memory and the instructions areconfigured to, with the at least one processor, cause the apparatus atleast: to obtain an indication related to a de-instantiation of at leastone virtualized network function providing services related to acommunication network, and to process the obtained indication fordetermining or recognizing the virtualized network function beingde-instantiated and for avoiding to conduct a communication attempt tothe virtualized network function to be de-instantiated.

According to a further example of an embodiment, there is provided, forexample, a method comprising receiving and processing an attach requestfrom a communication element of a communication network for attaching toa virtualized network function providing services related to thecommunication network, preparing a response to the attach request, andcausing transmission of the response to the requesting communicationelement, wherein the preparing of the response comprises including firstidentification data identifying the virtualized network function andsecond identification data identifying an intermediate network elementor network function being related to the virtualized network functionand to which messages related to the virtualized network function are tobe directed.

Furthermore, according to an example of an embodiment, there isprovided, for example, an apparatus comprising at least one processor,and at least one memory for storing instructions to be executed by theprocessor, wherein the at least one memory and the instructions areconfigured to, with the at least one processor, cause the apparatus atleast: to receive and process an attach request from a communicationelement of a communication network for attaching to a virtualizednetwork function providing services related to the communicationnetwork, to prepare a response to the attach request, and to causetransmission of the response to the requesting communication element,wherein the preparing of the response comprises including firstidentification data identifying the virtualized network function andsecond identification data identifying an intermediate network elementor network function being related to the virtualized network functionand to which messages related to the virtualized network function are tobe directed.

According to a further example of an embodiment, there is provided, forexample, a method comprising receiving and processing a message directedto a virtualized network function providing services related to acommunication network, checking whether the virtualized network functionis indicated to be still instantiated or not, and in case the result ofthe check is that the virtualized network function is de-instantiated,conducting a simulation process for replying to the received message onbehalf of the de-instantiated virtualized network function.

Furthermore, according to an example of an embodiment, there isprovided, for example, an apparatus comprising at least one processor,and at least one memory for storing instructions to be executed by theprocessor, wherein the at least one memory and the instructions areconfigured to, with the at least one processor, cause the apparatus atleast: to receive and process a message directed to a virtualizednetwork function providing services related to a communication network,to check whether the virtualized network function is indicated to bestill instantiated or not, and in case the result of the check is thatthe virtualized network function is de-instantiated, conduct asimulation process for replying to the received message on behalf of thede-instantiated virtualized network function.

In addition, according to embodiments, there is provided, for example, acomputer program product for a computer, comprising software codeportions for performing the steps of the above defined methods, whensaid product is run on the computer. The computer program product maycomprise a computer-readable medium on which said software code portionsare stored. Furthermore, the computer program product may be directlyloadable into the internal memory of the computer and/or transmittablevia a network by means of at least one of upload, download and pushprocedures.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present invention are described below, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 shows a diagram illustrating a general configuration ofcommunication networks where some examples of embodiments areimplementable;

FIG. 2 shows a diagram illustrating a configuration of a communicationnetwork where some examples of embodiments are implementable;

FIG. 3 shows a diagram illustrating a structure of identification datausable in some examples of embodiments;

FIG. 4 shows a flow chart of a processing conducted in a communicationnetwork control element or function acting as an indication provideraccording to some examples of embodiments;

FIG. 5 shows a flow chart of a processing conducted in a communicationnetwork control element or function acting as an indication obtaineraccording to some examples of embodiments;

FIG. 6 shows a diagram of a communication network control element orfunction acting as an indication provider according to some examples ofembodiments;

FIG. 7 shows a diagram of a communication network control element orfunction acting as an indication obtainer according to some examples ofembodiments;

FIG. 8 shows a flow chart of a processing conducted in a communicationnetwork control function acting as a virtualized network functionaccording to some examples of embodiments;

FIG. 9 shows a flow chart of a processing conducted in a communicationnetwork control element or function acting as an intermediate networkelement or function according to some examples of embodiments;

FIG. 10 shows a diagram of a communication network control functionacting as a virtualized network function according to some examples ofembodiments; and

FIG. 11 shows a diagram of a communication network control element orfunction acting as an intermediate network element or function accordingto some examples of embodiments.

DETAILED DESCRIPTION

In the last years, an increasing extension of communication networks,e.g. of wire based communication networks, such as the IntegratedServices Digital Network (ISDN), DSL, or wireless communicationnetworks, such as the cdma2000 (code division multiple access) system,cellular 3rd generation (3G) and fourth generation (4G) communicationnetworks like the Universal Mobile Telecommunications System (UMTS),enhanced communication networks based e.g. on LTE or LTE-A, cellular 2ndgeneration (2G) communication networks like the Global System for Mobilecommunications (GSM), the General Packet Radio System (GPRS), theEnhanced Data Rates for Global Evolution (EDGE), or other wirelesscommunication system, such as the Wireless Local Area Network (WLAN),Bluetooth or Worldwide Interoperability for Microwave Access (WiMAX),took place all over the world. Various organizations, such as the 3rdGeneration Partnership Project (3GPP), Telecoms & Internet convergedServices & Protocols for Advanced Networks (TISPAN), the InternationalTelecommunication Union (ITU), 3rd Generation Partnership Project 2(3GPP2), Internet Engineering Task Force (IETF), the IEEE (Institute ofElectrical and Electronics Engineers), the WiMAX Forum and the like areworking on standards for telecommunication network and accessenvironments.

Generally, for properly establishing and handling a communicationconnection between terminal devices such as a user device or userequipment (UE) and another communication network element or user device,a database, a server, host etc., one or more network elements such ascommunication network control elements, for example access networkelements like access points, base stations, eNBs etc. and core networkelements or functions, for example control nodes, support nodes, servicenodes, gateways etc. are involved, which may belong to differentcommunication network systems.

Such communication networks comprise, for example, a large variety ofproprietary hardware appliances. To launch a new network service oftenrequires yet another variety and finding the space and power toaccommodate these boxes is becoming increasingly difficult. Moreover,hardware-based appliances rapidly reach end of life. Due to this, it hasbeen considered to use, instead of hardware based network elements,virtually generated network functions, which is also referred to asnetwork functions virtualization. By means of software basedvirtualization technology, it is possible to consolidate many networkequipment types onto industry standard high volume servers, switches andstorage, which could be located in data centres, network nodes and inthe end user premises, for example.

FIG. 1 shows an example of a general configuration of communicationnetworks where some examples of embodiments are implementable. As shownin FIG. 1, network functions may be implemented as “traditional” networkelements, i.e. as dedicated hardware entities forming e.g. a traditionalcore network 100 of a communication network system consisting of e.g.GGSN, SGSN, PGW, MME, SGW, SGW-U, SGW-C, PGW-U, PGW-C etc. Alternativelyor additionally to the traditional core network, corresponding networkfunctions may also be implemented in the form of virtual networkfunctions (corresponding to network elements), i.e. as software runningon corresponding computing devices like servers or the like and forminga virtualized core network 200. Such a virtualized core networkcomprises, for example, software based PGW, MME, HSS etc., which executethe same or at least similar functions like corresponding hardware basednetwork elements. An access network subsystem 20, such as a RAN(comprising one or more BS or eNBs), may be controlled by and haveaccess to the core networks 100 and 200, as shown in FIG. 1.

It is to be noted that in a communication system both approaches may beused simultaneously and in a mixed manner, i.e. a core network beingemployed for services comprises virtual and “real” network elements orfunctions interacting which each other. Furthermore, also other networkfunctions besides those of a core network, such as network functions ofan access network element like an eNB or BS may be provided asvirtualized network functions.

NFV involves the implementation of network functions in software thatcan run on server hardware, and that can be moved to, or instantiatedin, various locations in the network or cloud/datacenters as required,without the need for installation of new equipment. It is to be notedthat NFV is able to support SDN by providing the infrastructure uponwhich the SDN software can be run. Furthermore, NFV aligns closely withthe SDN objectives to use commodity servers and switches.

Within SDN, it is possible to split control plane and user plane.Furthermore NFV may be implemented in such a manner that networkfunctions are instantiated and located within a so-called cloudenvironment, i.e. a storage and processing area shared by plural users,for example. For supporting the NFV using a cloud, a so-called cloudapplication manager (CAM) or the like (Cloud Framework, CFW) may beused. By means of this, it is for example possible to dynamicallyplacing elements/functions of a core network in a flexible manner (e.g.without or with decomposed SGW and/or PGW being split into SGW-C, PGW-C,SGW-U, PGW-U and OFC) into the cloud.

Dynamically placing the NF into the cloud allows also that all of theNFs or some parts or functions of the core network are dynamicallywithdrawn completely from the cloud (i.e. de-instantiated), while otherparts (legacy or SDN based or virtualized network functions) remain inthe network structure.

De-instantiated (or de-instantiation) means, for example, that a virtualnetwork function acting in a communication network in the virtualizednetwork part (see e.g. FIG. 1) is turned off, deactivated or made insome other manner not available for other communication network elementsor functions, i.e. the instantiation of the virtual network function inquestion is removed or cancelled, at least temporarily.

Examples of embodiments of the invention are related to a case where avirtualized network function, such as a virtualized core networkfunction (such as MME, SGW, PGW, HSS etc.) or a virtualized accessnetwork function (such as an eNB), a virtualized IMS function(such as aP-CSCF, IBCF, BGCF, MGCF etc.) is de-instantiated or shall bede-instantiated, i.e. at least partly cancelled or deactivated from thepoint of view of other network elements. For example, examples ofembodiments of the invention are related to scenario where an UEattaches or registers to an eNB which was connected to a (newly)instantiated virtualized MME or the like, and where this virtualized MMEis de-instantiated at a later point of time.

It is to be noted that in the following the term “attach” or “register”is to be understood as representing different forms of connecting orestablishing and maintaining a connection between a communicationelement like a UE and a network (i.e. one or more network elements orfunctions), such as “attach” in the sense of LTE systems, “register” inthe sense of IMS systems, etc. Similarly, the term “detach” or“deregister” is to be understood as representing different forms ofdisconnecting or cancelling a connection between a communication elementlike a UE and a network (i.e. one or more network elements orfunctions), such as “detach” in the sense of LTE systems, “deregister”in the sense of IMS systems, etc.

In the following, some examples of embodiments are described withreference to the drawings, wherein, as an example of a communicationnetwork, a cellular wireless communication network, such as an LTE orLTE-Advanced based system, is used. However, it is to be noted that thepresent invention is not limited to an application using such types ofcommunication systems, but is also applicable in other types ofcommunication systems, be it wireless systems, wired systems or systemsusing a combination thereof.

The following examples versions and embodiments are to be understoodonly as illustrative examples. Although the specification may refer to“an”, “one”, or “some” example(s) or embodiment(s) in several locations,this does not necessarily mean that each such reference is to the sameexample(s) or embodiment(s), or that the feature only applies to asingle example version or embodiment. Single features of differentembodiments may also be combined to provide other embodiments.Furthermore, terms like “comprising” and “including” should beunderstood as not limiting the described embodiments to consist of onlythose features that have been mentioned; such examples and embodimentsmay also contain features, structures, units, modules etc. that have notbeen specifically mentioned.

A basic system architecture of a communication system where examples ofembodiments are applicable may comprise a commonly known architecture ofone or more communication networks comprising a wired or wireless accessnetwork subsystem and a core network. Such an architecture may compriseone or more communication network control elements, access networkelements, radio access network elements, access service network gatewaysor base transceiver stations, such as a base station (BS), an accesspoint or an eNB, which control a respective coverage area or cell andwith which one or more communication elements or terminal devices suchas a UE or another device having a similar function, such as a modemchipset, a chip, a module etc., which can also be part of a UE orattached as a separate element to a UE, or the like, are capable tocommunicate via one or more channels for transmitting several types ofdata. Furthermore, core network elements such as gateway networkelements, policy and charging control network elements, mobilitymanagement entities, operation and maintenance elements, and the likemay be comprised.

The general functions and interconnections of the described elements,which also depend on the actual network type, are known to those skilledin the art and described in corresponding specifications, so that adetailed description thereof is omitted herein. However, it is to benoted that several additional network elements and signaling links maybe employed for a communication to or from a UE and a communicationnetwork besides those described in detail herein below.

The communication network is also able to communicate with othernetworks, such as a public switched telephone network or the Internet.The communication network may also be able to support the usage of cloudservices. It should be appreciated that BSs and/or eNBs or theirfunctionalities may be implemented by using any node, host, server oraccess node etc. entity suitable for such a usage. As indicated above,network elements, such as access network elements or core networkelements, may also be implemented by using a corresponding virtualizednetwork function.

Furthermore, the described network elements, such as terminal devices oruser devices like UEs, communication network control elements of a cell,like a BS or an eNB, access network elements like APs and the like, corenetwork elements etc. as well as corresponding functions as describedherein may be implemented by software, e.g. by a computer programproduct for a computer, and/or by hardware. For executing theirrespective functions, correspondingly used devices, nodes or networkelements may comprise several means, modules, units, components, etc.(not shown) which are required for control, processing and/orcommunication/signaling functionality. Such means, modules, units andcomponents may comprise, for example, one or more processors orprocessor units including one or more processing portions for executinginstructions and/or programs and/or for processing data, storage ormemory units or means for storing instructions, programs and/or data,for serving as a work area of the processor or processing portion andthe like (e.g. ROM, RAM, EEPROM, and the like), input or interface meansfor inputting data and instructions by software (e.g. floppy disc,CD-ROM, EEPROM, and the like), a user interface for providing monitorand manipulation possibilities to a user (e.g. a screen, a keyboard andthe like), other interface or means for establishing links and/orconnections under the control of the processor unit or portion (e.g.wired and wireless interface means, radio interface means comprisinge.g. an antenna unit or the like, means for forming a radiocommunication part etc.) and the like, wherein respective means formingan interface, such as a radio communication part, can be also located ona remote site (e.g. a radio head or a radio station etc.). It is to benoted that in the present specification processing portions should notbe only considered to represent physical portions of one or moreprocessors, but may also be considered as a logical division of thereferred processing tasks performed by one or more processors.

It should be appreciated that according to some examples, a so-called“liquid” or flexible network concept may be employed where theoperations and functionalities of a communication network controlelement or of another entity of the communication network, such as ofone or more of RAN elements like a BS or eNB, may be performed indifferent entities or functions, such as in a node, host or server, in aflexible manner. In other words, a “division of labour” between involvednetwork elements, functions or entities may vary case by case.

FIG. 2 shows a diagram illustrating a configuration of a communicationnetwork where some examples of embodiments are implementable. It is tobe noted that the configuration shown in FIG. 2 shows only thosedevices, network elements and/or parts which are useful forunderstanding principles underlying the example versions andembodiments. As also known by those skilled in the art, there may beseveral other network elements, functions or devices involved in acommunication network which are omitted here for the sake of simplicity.

In FIG. 2, a communication network configuration is illustrated which isfor example based on the 3GPP specifications. It is to be noted that thegeneral functions of the elements described in connection with FIG. 2 aswell as of reference points/interfaces between the elements are known tothose skilled in the art so that a detailed description thereof isomitted here for the sake of simplicity.

As shown in FIG. 2, in the exemplary communication network system, acommunication element such as a UE 10 is located in a communication areawhich is controlled by a respective communication network controlelement of an (radio) access network (RAN) comprising e.g. a basestation or eNB 20 or 25. It is to be noted that the UE may change itslocation within the network from one communication area or cell toanother. In the illustrated example, the eNB 20 will be referred to as anew RAN element or eNB indicating that it is the RAN to which the UE 10has changed or switched, while the eNB 25 will be referred to as an oldRAN element or eNB indicating that it is the RAN from which the UE 10has changed or switched (indicated also by the arrow at the UE 10).

The respective RAN elements 20 and 25 are connected with core networkelements of the EPC. The core network elements comprises, for example,MMEs 30 and 35, wherein MME 30 is assumed to be connected to the new eNB20 and thus referred to as new MME 30, while MME 35 is assumed to beconnected to the old eNB 25 and thus referred to as the old MME 35. TheMMEs 30 and 35 are connected with HSS 60. Furthermore, the MMEs are alsoconnected to a SGW which in turn is connected to a PGW. In the exampleillustrated in FIG. 2, only SGW 40 and PGW 50 are illustrated which arerelated to the old MME 35.

It is to be noted that the above described architecture indicated inFIG. 2 may be one being based on e.g. the 3GPP specification TS 23.401(see e.g. version 12.3.0), to which reference is made herewith.

Moreover, it is to be noted that according to examples of embodiments ofthe invention, at least one of the network elements (i.e. core networkelements or access network elements) is at least partly implemented byusing a virtualized network function. In the following, it is assumedthat the old MME 35 is such a virtualized network function. However,also other network elements can be implemented as virtualized networkfunctions in addition or alternatively to the MME 35.

Further elements shown in FIG. 2 are a global orchestrator element orfunction (GO or NUC) 70, a database 80 and a CAM (CFW) 90.

The GO 70 is used to (directly or indirectly via the CAM 90) manage thevirtualization of network functions, i.e. to instantiate (setup) andde-instantiate (delete) the respective NFs e.g. in a cloud environmentand to generate and manage the links to other network elements andfunctions of the communication network. For example, an SDN controller(not shown) may be implemented in the NFV. According to examples ofembodiment, some sort of interface from the GO 70 to thecloud/datacenter is provided (even a dedicated ATCA platform), which maybe designed to dynamically host software related to the virtualizednetwork function, such as a MME software, a SGW software etc, which canbe instantiated or withdrawn, or the like. It is to be noted that alsothe ATCA platform may be dynamically be loaded with the software neededfor acting as e.g. the SGW-U (or otherwise enabled).

It is to be noted that according to examples of embodiments the GO 70 isable to instantiate/de-instantiate any virtualized network function viathe CFW/CAM 90. Furthermore, there are also links between the respectivenetwork elements or function (wherever they may be located, i.e. in aphysical entity or in a cloud/datacenter) which are not completelyindicated in FIG. 2.

Furthermore, it is to be noted that according to examples of embodimentsthe type of network function which can be instantiated by the GO 70 (viathe CFW/CAM 90 or directly) is not limited to one type only. Forexample, besides a MME, network function which can be also instantiatedare any SGW or PGW and/or decomposed SGW-C and SGW-U or PGW-C and PGW-U.The type of the network function to be instantiated by the GO 70 may beselected and instructed by an operator according to a current need orthe like.

According to some examples of embodiments, the GO 70 is also able toprovide information regarding the virtualized NF to other networkelements and functions (which will be described later). This isindicated by arrow 75 which represents an indication for a correspondingcommunication or signaling to the network elements or functions beinginvolved (for example, a signaling to the MME 30 is concerned, inaccordance with the following description, but also other networkelements or functions may be recipients of a corresponding signalingcaused by the GO 70). The goal of this signaling is, for example, toinform the respective network element or function about thede-instantiation of a virtualized network function so as to suppress thesending of message (such as an identification request message) towardsthe de-instantiated network function (e.g. the old MME 35) as will bedescribed below.

The database 80 is used, for example, by the GO 70 as storage for statusinformation related to the virtualized network functions. For example,the database 80 is used to store and maintain information indicating astatus of all currently and formerly instantiated NFs, which informationis updated by the GO 70 (see e.g. signaling at M90). The statusinformation can be accessed by network elements by means of a query, forexample (see also arrows from the RAN elements and core network elementsin FIG. 2). It is to be noted that the database 80 may consist of one ormore centralized databases within the communication network, or by localdatabases located at respective network elements and entities, or acombination thereof. In case of (plural) local databases included inrespective network elements, the status information related to thevirtualized network function can be written and updated by means of asuitable signaling, e.g. in association with the signaling indicatedwith arrow 75.

In the following, as an initial starting point, it is assumed that theUE 10 is connected to the eNB 25 and registered/attached to thecommunication network via the MME 35, the SGW 40 and the PGW 50 by usinga network attachment procedure as described, for example, incorresponding specifications (see e.g. 3GPP TS23.401 v12.3.0).

Now, it is assumed that the UE 10 is turned off or the like and moved toanother communication area, e.g. to that of eNB 20. Here, it is notconnected to the old MME 35. Instead, the UE 10 has to register with anew MME, i.e. the new MME 30. In this procedure, at M10, the UE 10 sendsan attach request to the new eNB 20. The attach request comprises, forexample, an identification element or identification data which allowsthe receiving network elements (here the eNB 20 and also the MME 30) todetect that the requesting communication element was already attached orconnected to the network. For example, the identification element ordata comprises an identification of network elements or functions, suchas of an MME (here the old MME 35) which can be used by the eNB 20 forconducting the network attach procedure. As one example, a correspondingidentification is comprised in a GUTI being provided in the “old”attachment to the MME 35. It is to be noted that the new MME 30 will beable to know, for example, due to the content of a GUTI the old MME.Furthermore, the eNB may select the new MME based on an indication inthe GUTI, e.g. the old GUMMEI.

FIG. 3 shows a diagram illustrating a structure of a GUTI being usableas an example of identification data usable in some examples ofembodiments.

Basically, the purpose of the GUTI is to provide an unambiguousidentification of the UE that does not reveal the UE or the userspermanent identity in the communication network. It also allows theidentification of the MME and network, and is used by the network andthe UE to establish the UE's identity during signaling between them inthe communication network. The GUTI has two main components. One is theGUMMEI being constructed from MCC, MNC and an MME identifier comprisingan MME group ID and an MME code, which uniquely identifies the MME whichallocated the GUTI. The other one is the M-TMSI that uniquely identifiesthe UE within the MME that allocated the GUTI.

Back to FIG. 2, after receiving the attach request, the new eNB 20derives the MME from identification information, e.g. the GUMMEI.Assuming that MME is not associated with the eNB 20, a new MME isselected, e.g. the new MME 30, and the attach request is forwarded inM20 to the new MME 30.

The new MME 30 may determine the old MME 35 by using the GUTI receivedfrom the UE 10 to derive the old MME address, and send an identificationrequest to the old MME in M30. The old MME 35 responds with anidentification response (see M30).

The new MME 30 may send an attach accept message to the new eNB 20(M20), wherein again identification data such as a “new” GUTI isincluded if the new MME 30 allocates a new GUTI. Furthermore, a locationupdate procedure with the HSS 60 is conducted (see M40).

In the meantime, the old MME 35 may conduct a cancel location procedure(M50) with HSS 60, and a session delete procedure with the old SGW 40and old PGW 50 (see M60 and M70).

It is to be noted that the above described attach procedure is only asimplified example. A more detailed procedure may be based, for example,on that described in 3GPP TS23.401 v12.3.0.

As indicated above, according to some examples of embodiments, at leastone of the network elements shown in FIG. 2 is assumed to be avirtualized network function, for example the old MME 35.

Assuming now a situation where the virtualized old MME 35 had beende-instantiated (e.g. because it was not needed anymore) in themeantime, i.e. before the UE 10 starts the attach procedure with the newRAN (eNB 20) after having been deactivated or the like. In this case,the new MME 30 would not succeed with its communication attempt towardsthe old MME 35. That is, the signaling related to M30 is not responded.In this case, a delay in the set-up procedure for the UE 10 with the neweNB 20 occurs, e.g. due to repeated communication attempts by the newMME 30, which would inhibit to decrease an overall delay in userexperience when implementing virtualized network functions. For example,it may be required that any entity sending e.g. a GTP-C signalingmessage is mandated to reliable transfer the message. That especiallymeans that the sender has to repeat sending until it is was successfullyacknowledged or the entity detects the final failure after severalretries. Anyhow, this leads to a delay of the set-up.

According to some examples of embodiments of the invention, thissituation is overcome by the following measures. That is, according tothe present examples of embodiments, when it is determined that avirtualized network function providing services related to acommunication network (such as the MME 35) is de-instantiated or will bede-instantiated, a specific indication informing about thede-instantiation of the virtualized network function is prepared andsent to network entities, elements or functions or databases which canuse this information so as to avoid unsuccessful communication attemptsas that described above with regard to the signaling in M30.

It is to be noted that the determination of the de-instantiation of thevirtualized network function is achievable by different measures,according to examples of embodiments of the invention. Basically, anymeasure allowing the respective control network element or function(such as the GO 70) to know that a virtualized network element orfunction is de-instantiated or will be de-instantiated is suitable forthe determination of the de-instantiation of the virtualized networkfunction. For example, the determination is achieved when the GO 70 (oranother control entity) decides that the virtualized network function isnot needed anymore and hence to be de-instantiated, wherein acorresponding de-instantiation procedure for the virtualized networkfunction is then to be conducted, resulting in the determination thatthe virtualized network function is de-instantiated. Alternatively, thede-instantiation of the virtualized network function is initiated byother means (a datacenter operator, due to a failure, etc.), and acorresponding information is obtained by the GO 70 or the like, whereinthen the determination that the virtualized network function isde-instantiated is achieved by recognizing the correspondinginformation. As a further alternative, the GO 70 (or another controlentity) conducts a measurement or the like in order to detect whetherthe virtualized network element is still existing, wherein in case themeasurement is negative, this is used as determination that thevirtualized network function is de-instantiated.

According to some examples of embodiments, as the indication, a detachprocedure, which is initiated by a corresponding network element orfunction, is conducted. One of possible network elements or functionscapable of initiating such a detach procedure is, for example, the HSS60, which starts a HSS-initiated detach procedure.

By means of the detach procedure, subscription data in at least onenetwork element or function can be removed, for example subscriptiondata in the HSS 60, the MME 35, the UE 10 are removed. The indication orcommand to conduct the detach procedure is for example accompanied by acause code or the like, such as a cause “subscription withdrawn”, whichis caused to be transmitted before the virtualized MME 35 isde-instantiated. The detach procedure may be instructed, for example, bythe GO 70 via a cloud application manager (CAM/CFW 90) and/or an OAMcentre (not shown).

One example of subscription data is the GUTI (see e.g. FIG. 3). The GUTIcontains the ID of the last/old MME (MME Code and MME group ID). Bymeans of the detach procedure (e.g. the HSS-initiated detach procedure)with “subscription withdrawn”, the old GUTI is deleted at the UE 10.

According to some further examples of embodiments, the detach procedureis executed in a combined manner. That is, a command is provided whichallows to execute a bulk detach procedure (e.g. a bulk “HSS-initiateddetach” command) for the whole virtualized network function to bede-instantiated (e.g. for the MME 35). That is, it is not necessary toindividually detach each and every UE from the network. Instead, byusing such a new bulk command, all UE currently registered with thevirtualized MME which is to be de-instantiated are detached at once. Forexample, in case of bulk instruction, an ID of the element beingde-instantiated (e.g. the old MME 35) is provided. Network elements orfunctions receiving an instruction related to the bulk detach procedurethen searches its subscription data (e.g. in a correspondingsubscription database) for network elements (UEs and/or other networkelements) being associated with the function to be de-instantiated onthe basis of this ID. For the positive results of the search, the detachprocedure is conducted.

Alternatively or additionally to the above described detach procedure,according to some further examples of embodiments, the indicationprovided allows to suppress a communication attempt to thede-instantiated virtualized network function directly in the new networkelement (e.g. in the new MME 30). That is, for example, the query(identification request in M30) to the old MME 35 is inhibited.

For example, a UE may decide on itself to detach from the virtualizedMME 35 at any arbitrary time even before a detach procedure like thatdescribed above (e.g. a HSS-initiated detach procedure) was triggered.In that case, the identification data (such as the GUTI) is not deletedin the UE and not necessarily deleted immediately in the MME (and theHSS). Therefore, there are still cases were the UE 10 may register witha new MME 30 with its old identification data (the old GUTI allocated bythe old virtualized MME 35). Still, since the old MME 35 isde-instantiated at this time, the new MME 30 is not able to contact theold (virtualized) MME 35.

Therefore according to the present examples of embodiments, aninformation is provided to any network element or function which may beinterested in the information (e.g. all network elements or functionswhich may contact the de-instantiated network function, such as networkelements or functions having the same task, like remaining MMEs(virtualized or physical) of the network, are informed that one or morevirtualized network functions (such as the MME 35) had beende-instantiated in the meantime. The information is provided, forexample, by the GO 70 e.g. via OAM interface.

Hence, when the new MME 30 receives an initial attach request (M20 inFIG. 2), before starting to send the identification request to any oldMME (or SGSN) indicated e.g. in identification information or datareceived from the UE 10 (such as the GUTI), the new MME 30 checks(internally or externally) whether the indicated MME/SGSN is avirtualized MME/SGSN for which an information has been received that itexist or is de-instantiated. In case it was reported that the MME/SGSNin question is not to instantiate anymore, the new MME 30 skips thesending of the identification request towards the old MME/SGSNcompletely as it will not be successful at all.

Similarly, according to some examples of embodiments, other networkentities are informed about the de-instantiation of the virtualizednetwork functions (such as MME 35) for similar purposes. For example,any HSS (virtualized or not) is informed accordingly about thede-instantiation of the MME.

According to some further examples of embodiments, alternatively oradditionally to the above described procedures, database 80 as shown inFIG. 2 is implemented for supporting the control process in case avirtualized network function is de-instantiated.

For example, the database 80 is maintained by the GO (or NUC) 70 inorder to list a status of current and formerly instantiated NF. Forinstance, if a particular MME/SGSN or SGW-C or PGW-C (or SGW and PGW) isactive it is marked as such in the database. In addition, in case the GO70 decides or recognizes by other means that a virtualized networkfunction does not longer exist, the GO 70 updates the correspondingentry in the database 80. It is to be noted that the database may be acentralized database (as indicated in FIG. 2) and/or may be implementedas a local database to several or all of the network elements of thecommunication network. Information to the database 80 from the GO 70 istransmitted e.g. by signalling M90 (in case of a centralized database)or by means of signalling related to signalling according to arrow 75 inFIG. 2 (in case of local databases).

Hence, in case any of the existing network elements or functions needsto contact a “potentially” virtualized network function (which, asdescribed above, may no longer be instantiated), the network elementsends a query to the central database 80 (or queries a local database)in order to learn whether the network function in question is stillinstantiated. That is, the indication regarding the state of thevirtualized network function is obtained by means of the correspondingquery to a central (i.e. external) or local (i.e. internal) database.Thus, as described above, it is possible to recognize that it is notneeded to try to contact the corresponding NF, since it was already torndown (de-instantiated). That is, a network element or function, such asthe new MME 30, queries the central or local database in order tolearn/detect whether the old MME 35 is torn down or not, which allows tosuppress unneeded retries and a corresponding delay. In case theinformation is obtained that the old MME 35 is de-instantiated, the newMME 35 may also start a default identification request procedure withthe UE 10 as early as possible (e.g. by means of signalling M15).

According to further examples of embodiments, in case the MME 35 isde-instantiated, also the RAN (such as the eNB 25 via the S1-MMEinterface) is impacted. Therefore, in the virtualised environment, theeNB is informed about the de-instantiation as well.

For example, in case of the initialisation of a SCTP association, theeNB 25 retransmit repeatedly messages via the S1-MME (see e.g.signalling on M80) until the eNB 25 finally considers that the endpointis unreachable. In this case, it enters a CLOSED state and may possiblyreport the failure to an upper layer. Thus, the eNB 25 may repeat tosend messages to the MME 35 although the GO/NUC already knows about thepossible/intended/factual termination of the MME 35. Therefore, the RAN(e.g. eNB 25) obtains the information of the de-instantiation of the MME35 and can thus avoid an unsuccessful communication attempt and hence awaste of resources. For example, the eNB 25 may query the database 80,e.g. when a communication attempt to the MME 35 was not acknowledged orbefore any communication attempt towards the MME 35 is started.

While above described examples are related to a de-instantiation of anMME (i.e. MME 35) as a virtualized network function, as indicatedbeforehand, also other scenarios are possible. For example, according tofurther examples, in case it is determined that, as a virtualizednetwork function, e.g. a network function like a PGW(-C/U) or SGW(-C/U)is de-instantiated (for example, the GO 70 decides or knows about thede-instantiation thereof), a network element or function which requiressuch an information, like an MME, is informed that the correspondingPGW(-C/U) or SGW(-C/U) functions are de-instantiated. The reason is thatin case an PGW and SGW selection process is located in the networkelement or function in question (e.g. at the MME), the de-instantiatednetwork function (i.e. the PGW(-C/U) or SGW(-C/U)) should not beconsidered in the selection process, as the corresponding instanceceased to exist.

It is to be noted that while the above described example of embodimentsis related to a scenario implemented in an LTE system (i.e. eNB andEPC), examples of embodiments are also applicable to other communicationsystems and implementations. For example, examples of embodiments can beimplemented in IMS or the like, for instance with regard to virtualizedfunctions related to an P-CSCF, IBCF, BGCF, MGCF and on the like. In theIMS, it is to be noted that an UE performs a (SIP) registrationprocedure which is comparable to the LTE/EPC/eNB attachment proceduredescribed above, so that the same principles as described with regard tothe attachment procedure can be applied there as well.

Consequently, the same procedures as described above with regard to NFVin LTE systems may be used for other systems, such as for NFV in IMS,and the same principle can be applied.

FIG. 4 shows a flow chart of a processing conducted in a communicationnetwork control element or function acting as an indication providerindicating the de-instantiation of a network function, according to someexamples of embodiments. For example, the processing is executed by oneof a communication network control element or communication networkcontrol function acting as a global orchestrator for implementingvirtualized network functions, the virtualized network function to bede-instantiated, or an OAM element or function of a communicationnetwork. According to some examples of embodiments, the virtualizednetwork function to be de-instantiated is related to a communicationnetwork control function of the communication network (e.g. core networkfunction, access network function, IMS network function, etc.).

In S100, it is determined that at least one virtualized network functionproviding services related to the communication network is to bede-instantiated, i.e. to be deactivated or the like.

In S110, an indication related to the de-instantiation of the at leastone virtualized network function is prepared.

For example, the indication related to the de-instantiation of the atleast one virtualized network element comprises an instruction forconducting a detach procedure, such as a HSS initiated detach procedure.The detach procedure comprises, for example, to delete the storedsubscription data related to the at least one virtualized networkelement to be de-instantiated. According to some examples ofembodiments, the instruction for conducting the detach procedurecomprises a specific cause indication for a withdrawal of a subscriptionwith regard to the at least one virtualized network element to bede-instantiated. For example, subscription data containing an indicationof the virtualized network function are to be deleted, such as anidentification element assigned to a UE and including identificationinformation of the virtualized network element to be de-instantiated(e.g. GUTI for a UE).

According to further examples, the instruction may be a bulk instructionallowing for conducting the detach procedure for all communicationelements (i.e. UEs) being currently registered for the at least onevirtualized network element to be de-instantiated.

Alternatively or additionally, the indication related to thede-instantiation of the at least one virtualized network elementcomprises an identification information indicating that the at least onevirtualized network element to be de-instantiated is de-instantiated andnot available anymore.

In S120, a transmission of the prepared indication to at least one of anetwork element of the communication network, a network function of thecommunication network and a database to which network elements ornetwork functions of the communication network have access is caused.

For example, the transmission of the identification information iscaused to at least one of a network element of the communication networkand a network function of the communication network which potentiallycontacts the at least one virtualized network element to bede-instantiated. This allows, for example, that the de-instantiatedvirtualized network function is not contacted at all anymore.

According to some examples of embodiments, the prepared indication iscaused to be sent to at least one of a communication element comprisinga terminal device or UE capable of communicating in the communicationnetwork, a RAN network element or RAN network function, a networkelement or network function of a core network part of the communicationnetwork, and a database to which network elements or network functionsof the communication network have access, wherein the database iscomprised in at least one of a centralized database of the communicationnetwork and a local database comprised in one or more of the networkelements or network functions of the communication network.

FIG. 5 shows a flow chart of a processing conducted in a communicationnetwork control element or function acting as an obtainer of anindication indicating the de-instantiation of a virtualized networkfunction, according to some examples of embodiments. For example, theprocessing is executed by one of a communication element comprising aterminal device or UE capable of communicating in a communicationnetwork, a RAN network element or network function of the communicationnetwork, and a network element or network function of a core networkpart of the communication network. According to some examples ofembodiments, the virtualized network function to be de-instantiated isrelated to a communication network control function of the communicationnetwork (e.g. core network function, access network function, IMSnetwork function, etc.).

In S200, the indication related to the de-instantiation of at least onevirtualized network function providing services related to thecommunication network is obtained, for example received by means of asuitable signaling. For example, the indication related to thede-instantiation of the at least one virtualized network function isobtained from one of a communication network control element orcommunication network control function acting as a global orchestratorfor implementing virtualized network functions, the virtualized networkfunction to be de-instantiated, and an OAM element of the communicationnetwork. As described above, also a query at a database (internal/localor external/centralized) may act as the source for obtaining theindication related to the de-instantiation.

In S210, the obtained indication is processed for determining orrecognizing the virtualized network function being de-instantiated.

Then, in S220, a processing is conducted so as to avoid a communicationattempt to the virtualized network function to be de-instantiated isavoided.

For example, when, as the indication related to the de-instantiation ofthe at least one virtualized network element, an instruction forconducting a detach procedure is obtained, wherein the detach proceduremay include a deletion of stored subscription data related to the atleast one virtualized network element to be de-instantiated, the detachprocedure is executed accordingly. According to some examples ofembodiments, the instruction for conducting the detach procedurecomprises a specific cause indication for a withdrawal of a subscriptionwith regard to the at least one virtualized network element to bede-instantiated. For example, subscription data containing an indicationof the virtualized network function are deleted, such as anidentification element assigned to a UE and including identificationinformation of the virtualized network element to be de-instantiated(e.g. GUTI for a UE).

According to further examples, the instruction may be a bulk instructionallowing for conducting the detach procedure for all communicationelements (i.e. UEs) being currently registered for the at least onevirtualized network element to be de-instantiated.

Alternatively or additionally, the indication related to thede-instantiation of the at least one virtualized network elementcomprises an identification information indicating that the at least onevirtualized network element to be de-instantiated is de-instantiated andnot available anymore.

According to some examples of embodiments, the processing comprises tocheck, when a communication attempt is to be conducted to a networkelement or network function of the communication network, e.g. inconnection with a registration or identification procedure, whether thenetwork element or network function is indicated in the identificationinformation indicating the at least one virtualized network element tobe de-instantiated as being de-instantiated and not available anymore.In case the result of the check is affirmative, i.e. the network elementis indicated to be de-instantiated, the communication attempt to thevirtualized network function being de-instantiated is immediatelyskipped. Instead, for example, a default initial registration process orthe like is executed.

Furthermore, according to some example versions of the disclosure, adatabase to which network elements or network functions of thecommunication network have access, may be queried. The database iscomprised, for example, in at least one of a centralized database of thecommunication network and a local database comprised in one or more ofthe network elements or network functions of the communication network,wherein the indication related to a de-instantiation of at least onevirtualized network function is obtained from the database.

FIG. 6 shows a diagram of a communication network control element orfunction acting as an indication provider according to some examples ofembodiments, which is configured to implement the control procedure asdescribed in connection with some of the examples of embodiments. It isto be noted that the communication network control element or function,like the GO 70, a virtualized network function like the MME 35, etc.,which is shown in FIG. 6, may comprise further elements or functionsbesides those described herein below. Furthermore, even though referenceis made to a communication network control element or function, theelement or function may be also another device or function having asimilar task, such as a chipset, a chip, a module etc., which can alsobe part of a communication network control element or function orattached as a separate element or function to a communication networkcontrol element or function, or the like. It should be understood thateach block and any combination thereof may be implemented by variousmeans or their combinations, such as hardware, software, firmware, oneor more processors and/or circuitry.

The communication network control element or function shown in FIG. 6may comprise a processing function, a control unit or a processor 71,such as a CPU or the like, which is suitable for executing instructionsgiven by programs or the like related to the control procedure. Theprocessor 71 may comprise one or more processing portions or functionsdedicated to specific processing as described below, or the processingmay be run in a single processor or processing function. Portions forexecuting such specific processing may be also provided as discreteelements or within one or more further processors, processing functionsor processing portions, such as in one physical processor like a CPU orin one or more physical or virtual entities, for example. Reference sign72 denotes transceiver or input/output (I/O) units or functions(interfaces) connected to the processor or processing function 71. TheI/O units 72 may be used for communicating with one or more networkelements, such as communication elements like UEs, RAN element, corenetwork elements or functions, databases/datacenters and the like. TheI/O units 72 may be a combined unit comprising communication equipmenttowards several network elements, or may comprise a distributedstructure with a plurality of different interfaces for different networkelements. Reference sign 74 denotes a memory usable, for example, forstoring data and programs to be executed by the processor or processingfunction 71 and/or as a working storage of the processor or processingfunction 71.

The processor or processing function 71 is configured to executeprocessing related to the above described control procedure. Inparticular, the processor or processing function 71 comprises asub-portion 710 as a processing portion which is usable for conducting ade-instantiation determination. The portion 710 may be configured toperform processing according to S100 of FIG. 4. Furthermore, theprocessor or processing function 71 comprises a sub-portion 711 usableas a portion for preparing an indication. The portion 711 may beconfigured to perform processing according to S110 of FIG. 4.Furthermore, the processor or processing function 71 comprises asub-portion 712 usable as a portion for transmitting the preparedindication. The portion 712 may be configured to perform a processingaccording to S120 of FIG. 4.

FIG. 7 shows a diagram of a communication network control element orfunction acting as an indication obtainer according to some examples ofembodiments, which is configured to implement the control procedure asdescribed in connection with some of the examples of embodiments. It isto be noted that the communication network control element or function,like a physical network element or virtualized network function being acore network control element or function like the MME 30, an accessnetwork element like a RAN network element, such as an eNB (e.g. eNB 20)etc., which is shown in FIG. 7, may comprise further elements orfunctions besides those described herein below. Furthermore, even thoughreference is made to a communication network control element orfunction, the element or function may be also another device or functionhaving a similar task, such as a chipset, a chip, a module etc., whichcan also be part of a communication network control element or functionor attached as a separate element or function to a communication networkcontrol element or function, or the like. It should be understood thateach block and any combination thereof may be implemented by variousmeans or their combinations, such as hardware, software, firmware, oneor more processors and/or circuitry.

The communication network control element or function shown in FIG. 7may comprise a processing function, a control unit or a processor 31,such as a CPU or the like, which is suitable for executing instructionsgiven by programs or the like related to the control procedure. Theprocessor 31 may comprise one or more processing portions or functionsdedicated to specific processing as described below, or the processingmay be run in a single processor or processing function. Portions forexecuting such specific processing may be also provided as discreteelements or within one or more further processors, processing functionsor processing portions, such as in one physical processor like a CPU orin one or more physical or virtual entities, for example. Reference sign32 denotes transceiver or input/output (I/O) units or functions(interfaces) connected to the processor or processing function 31. TheI/O units 32 may be used for communicating with one or more networkelements, such as communication elements like UEs, RAN elements, corenetwork elements or functions, a GO element, an OAM element, an externaldatabase and the like. The I/O units 32 may be a combined unitcomprising communication equipment towards several network elements, ormay comprise a distributed structure with a plurality of differentinterfaces for different network elements. Reference sign 34 denotes amemory usable, for example, for storing data and programs to be executedby the processor or processing function 31 and/or as a working storageof the processor or processing function 31. It is to be noted that incase a local database for storing information regarding the state of thevirtualized network functions is to be provided, a part of memory 34 maybe used for this, or a separate storage entity (not shown) may beprovided for this purpose. In this case, corresponding information canbe written/updated, for example by means of a corresponding signalingfrom the GO 70.

The processor or processing function 31 is configured to executeprocessing related to the above described control procedure. Inparticular, the processor or processing function 31 comprises asub-portion 310 as a processing portion which is usable for obtaining ade-instantiation indication. The portion 310 may be configured toperform processing according to S200 of FIG. 5. Furthermore, theprocessor or processing function 31 comprises a sub-portion 311 usableas a portion for processing the indication. The portion 311 may beconfigured to perform processing according to S210 of FIG. 5.Furthermore, the processor or processing function 31 comprises asub-portion 312 usable as a portion for avoiding a communicationattempt. The portion 312 may be configured to perform a processingaccording to S220 of FIG. 5.

Next, a further example of embodiments is described.

While the above described examples are related to a configuration whereit is determined that a virtualized network function is to bede-instantiated and a corresponding indication is provided to thecommunication network so as to be obtainable by other network elementsor functions, the present examples of embodiments are related to afurther approach.

Specifically, an intermediate network element or function (virtualizedor physical) is provided. When a virtualized network function (which maybe de-instantiated at a later point of time, for example), such as theMME 35, conducts an attach processing for a communication element (UE)of a communication network, it prepares a response to the attach requestincluding first identification data identifying the virtualized networkfunction (MME 35) and second identification data identifying theintermediate network element or network function (which may alsoreferred to as a “light” MME). To this intermediate network element orfunction, messages related to the virtualized network function (MME 35)are to be directed by other network elements.

Now, when the intermediate network element or function receives such amessage directed to the virtualized network function (MME 35), it checkswhether the virtualized network function (MME 35) is indicated to bestill instantiated or not. In case the result of the check is that thevirtualized network function is de-instantiated, a simulation processfor replying to the received message on behalf of the de-instantiatedvirtualized network function is conducted.

According to some examples of embodiments, the check may be based oninformation like that described in connection with the above describedembodiments, i.e. by information provided from the GO 70 and/orretrieved from database 80.

That is, according to the present examples of embodiments, thevirtualized network function, such as the MME 35, is configured in sucha manner that if it prepares a response to the attach request, e.g.providing identification data (such as a new GUTI), then this newidentification data (the new GUTI) includes also identification datawhich resolve to the intermediate network element or function (the“light” MME). This intermediate network element or function isconfigured, for example, to simulate a corresponding network function,i.e. it simulates a simple MME which is capable to correctly response toan identification request or the like received from any new MME (e.g.MME 30) and the cancel location procedure from the HSS 60, in case thevirtualized MME was de-instantiated.

According to some examples of embodiments, the intermediate networkelement (e.g. the light MME) is always contacted first. In case thevirtualized network function is (still) instantiated, the intermediatenetwork element or function forwards the message (e.g. a request) to thecorrect MME.

According to some examples of embodiments, the intermediate networkelement or function is a centralized entity. Furthermore, it may beconfigured to host all remaining subscription data related to UEs of allvirtual network functions which may be de-instantiated, such asvirtualized MMEs. Furthermore, a streamlined software or the like isprovided in the intermediate network element or function which is simplyable to act and respond in accordance to the rules provided for thecorresponding virtualized network function (e.g. according to 3GPPstandards for an MME), i.e. to act on behalf of the (then)de-instantiated network function.

It is to be noted that according to examples of embodiments,identification data such as addresses or the like for both thevirtualized network function and the intermediate network element orfunction (e.g. for the MME 35 and the light MME) are to be provided inidentification data such as the GUTI or by means of a separateinformation element to be signalled to the UE.

FIG. 8 shows a flow chart of a processing conducted in a communicationnetwork control function acting as a virtualized network functionaccording to some examples of embodiments, which may be de-instantiatedat some (unknown) point of time. For example, the processing is executedby a virtualized network function providing services related to acommunication network, e.g. related to a communication network controlfunction of the communication network (e.g. core network function,access network function, IMS network function, etc.).

In S300, an attach request e.g. from a communication element of acommunication network, like a UE, for attaching to the virtualizednetwork function is received and processed.

In S310, a response to the attach request is prepared. According to someexamples of embodiments, in the preparation of the response, firstidentification data identifying the virtualized network function areincluded. Furthermore, second identification data identifying anintermediate network element or network function are included, whereinthe intermediate network element or network function is related to thevirtualized network function, and wherein messages being related to thevirtualized network function are to be directed thereto.

According to some examples of embodiments, the first and secondidentification data are included in identification data such as a GUTIassigned to the requesting UE, wherein the second identification dataresolve to the intermediate network element or network function.

In S320, a transmission of the response to the requesting communicationelement is caused.

FIG. 9 shows a flow chart of a processing conducted in a communicationnetwork control element or function acting as an intermediate networkelement or function according to some examples of embodiments.Specifically, the intermediate network element or function may berelated to a virtualized network function which may be de-instantiatedat some (unknown) point of time, wherein the virtualized networkfunction may provide services related to a communication network, forexample it may be related to a communication network control function ofthe communication network (e.g. core network function, access networkfunction, IMS network function, etc.). The processing may be executed,for example, by a communication network control element or communicationnetwork control function acting as the intermediate network element orintermediate network function.

In S400, a message directed to a virtualized network function isreceived and processed. According to some examples of embodiments, themessage directed to the virtualized network function is received fromone of a communication element comprising a terminal device or UEcapable of communicating in the communication network, a RAN networkelement or network function of the communication network, and a networkelement or network function of a core network part of the communicationnetwork.

In S410, it is checked whether the virtualized network function isindicated to be still instantiated or not. According to some examples ofembodiments, the check is based on that subscription data ofcommunication elements of the communication network attached tovirtualized network functions are hosted. Furthermore, indications forvirtualized network functions are stored which indicate whether thevirtualized network functions are de-instantiated or not.

In S420, the check is evaluated. In case the result of the check is thatthe virtualized network function is de-instantiated (NO in S420), theprocessing proceeds to S430. Otherwise, in case the result of the checkis that the virtualized network function is (still) instantiated (YES inS420), the processing proceeds to S440.

In S430, a simulation process for replying to the received message onbehalf of the (de-instantiated) virtualized network function isconducted. For example, according to examples of embodiments, thesimulation process comprises replying to the received message on behalfof the de-instantiated virtualized network function on the basis of thestored subscription data.

Otherwise, in S440, the received message is forwarded to the virtualizednetwork function.

Then, the processing is ended.

FIG. 10 shows a diagram of a communication network control functionacting as a virtualized network function according to some examples ofembodiments, which is configured to implement a control procedure asdescribed in connection with some of the examples of embodiments. It isto be noted that the virtualized network function, like a communicationnetwork control function of the communication network (e.g. core networkfunction, access network function, IMS network function, etc.), e.g. acore network control function like the MME 35 etc., which is shown inFIG. 10, may comprise further functions besides those described hereinbelow. Furthermore, even though reference is made to a communicationnetwork control function, the function may be also another functionhaving a similar task, such as a module etc., which can also be part ofa communication network control function or attached as a separatefunction to a communication network control function, or the like. Itshould be understood that each block and any combination thereof may beimplemented by various means or their combinations, such as hardware,software, firmware, one or more processors and/or circuitry.

The communication network control function shown in FIG. 10 may comprisea processing function, a control unit or a processor 351, such as a CPUor the like, which is suitable for executing instructions given byprograms or the like related to the control procedure. The processor 351may comprise one or more processing portions or functions dedicated tospecific processing as described below, or the processing may be run ina single processor or processing function. Portions for executing suchspecific processing may be also provided as discrete elements or withinone or more further processors, processing functions or processingportions, such as in one physical processor like a CPU or in one or morephysical or virtual entities, for example. Reference sign 352 denotestransceiver or input/output (I/O) units or functions (interfaces)connected to the processor or processing function 351. The I/O units 352may be used for communicating with one or more network elements, such ascommunication elements like UEs, RAN elements, core network elements orfunctions, a GO element, an OAM element and the like. The I/O units 352may be a combined unit comprising communication equipment towardsseveral network elements, or may comprise a distributed structure with aplurality of different interfaces for different network elements.Reference sign 354 denotes a memory usable, for example, for storingdata and programs to be executed by the processor or processing function351 and/or as a working storage of the processor or processing function351.

The processor or processing function 351 is configured to executeprocessing related to the above described control procedure. Inparticular, the processor or processing function 351 comprises asub-portion 3510 as a processing portion which is usable for processingan attach request. The portion 3510 may be configured to performprocessing according to S300 of FIG. 8. Furthermore, the processor orprocessing function 351 comprises a sub-portion 3511 usable as a portionfor preparing a response. The portion 3511 may be configured to performprocessing according to S310 of FIG. 8. Furthermore, the processor orprocessing function 351 comprises a sub-portion 3512 usable as a portionfor transmitting a response. The portion 3512 may be configured toperform a processing according to S320 of FIG. 8.

FIG. 11 shows a diagram of a communication network control element orfunction acting as an intermediate network element or function accordingto some examples of embodiments, which is configured to implement thecontrol procedure as described in connection with some of the examplesof embodiments. It is to be noted that the communication network controlelement or function, like a physical network element or virtualizednetwork function being a core network control element or function, whichis shown in FIG. 11, may comprise further elements or functions besidesthose described herein below. Furthermore, even though reference is madeto a communication network control element or function, the element orfunction may be also another device or function having a similar task,such as a chipset, a chip, a module etc., which can also be part of acommunication network control element or function or attached as aseparate element or function to a communication network control elementor function, or the like. It should be understood that each block andany combination thereof may be implemented by various means or theircombinations, such as hardware, software, firmware, one or moreprocessors and/or circuitry.

The communication network control element or function 90 shown in FIG.11 may comprise a processing function, a control unit or a processor 91,such as a CPU or the like, which is suitable for executing instructionsgiven by programs or the like related to the control procedure. Theprocessor 91 may comprise one or more processing portions or functionsdedicated to specific processing as described below, or the processingmay be run in a single processor or processing function. Portions forexecuting such specific processing may be also provided as discreteelements or within one or more further processors, processing functionsor processing portions, such as in one physical processor like a CPU orin one or more physical or virtual entities, for example. Reference sign92 denotes transceiver or input/output (I/O) units or functions(interfaces) connected to the processor or processing function 91. TheI/O units 92 may be used for communicating with one or more networkelements, such as communication elements like UEs, RAN elements, corenetwork elements or functions, a GO element, an OAM element and thelike. The I/O units 92 may be a combined unit comprising communicationequipment towards several network elements, or may comprise adistributed structure with a plurality of different interfaces fordifferent network elements. Reference sign 94 denotes a memory usable,for example, for storing data and programs to be executed by theprocessor or processing function 91 and/or as a working storage of theprocessor or processing function 91.

The processor or processing function 91 is configured to executeprocessing related to the above described control procedure. Inparticular, the processor or processing function 91 comprises asub-portion 910 as a processing portion which is usable for processing amessage (e.g. Identification Request). The portion 910 may be configuredto perform processing according to S400 of FIG. 9. Furthermore, theprocessor or processing function 91 comprises a sub-portion 911 usableas a portion for checking an instantiation state. The portion 911 may beconfigured to perform processing according to S910 of FIG. 9.Furthermore, the processor or processing function 91 comprises asub-portion 912 usable as a portion for forwarding the message. Theportion 912 may be configured to perform a processing according to S440of FIG. 9. Additionally, the processor or processing function 91comprises a sub-portion 913 usable as a portion for conducting asimulation processing. The portion 913 may be configured to perform aprocessing according to S430 of FIG. 9.

According to an example of embodiments, there is provided an apparatuscomprising means for determining that at least one virtualized networkfunction providing services related to a communication network is to bede-instantiated, means for preparing an indication related to thede-instantiation of the at least one virtualized network function, andmeans for causing transmission of the prepared indication to at leastone of a network element of the communication network, a networkfunction of the communication network and a database to which networkelements or network functions of the communication network have access.

According to another example of embodiments, there is provided anapparatus comprising means for obtaining an indication related to ade-instantiation of at least one virtualized network function providingservices related to a communication network, and means for processingthe obtained indication for determining or recognizing the virtualizednetwork function being de-instantiated and for avoiding to conduct acommunication attempt to the virtualized network function to bede-instantiated.

According to still another example of embodiments, there is provided anapparatus comprising means for receiving and processing an attachrequest from a communication element of a communication network forattaching to a virtualized network function providing services relatedto the communication network, means for preparing a response to theattach request, and means for causing transmission of the response tothe requesting communication element, wherein the preparing of theresponse comprises including first identification data identifying thevirtualized network function and second identification data identifyingan intermediate network element or network function being related to thevirtualized network function and to which messages related to thevirtualized network function are to be directed.

According to yet another example of embodiments, there is provided anapparatus comprising means for receiving and processing a messagedirected to a virtualized network function providing services related toa communication network, means for checking whether the virtualizednetwork function is indicated to be still instantiated or not, and meansfor conducting, in case the result of the check is that the virtualizednetwork function is de-instantiated, a simulation process for replyingto the received message on behalf of the de-instantiated virtualizednetwork function.

It should be appreciated that

-   -   an access technology via which signaling is transferred to and        from a network element may be any suitable present or future        technology, such as WLAN (Wireless Local Access Network), WiMAX        (Worldwide Interoperability for Microwave Access), LTE, LTE-A,        Bluetooth, Infrared, and the like may be used; Additionally,        embodiments may also apply wired technologies, e.g. IP based        access technologies like cable networks or fixed lines.    -   a user device (also called UE, user equipment, user terminal,        terminal device, etc.) illustrates one type of an apparatus to        which resources on the air interface may be allocated and        assigned, and thus any feature described herein with a user        device may be implemented with a corresponding apparatus, such        as a relay node. An example of such a relay node is a layer 3        relay (self-backhauling relay) towards a base station or eNB.        The user device typically refers to a portable computing device        that includes wireless mobile communication devices operating        with or without a subscriber identification module (SIM),        including, but not limited to, the following types of devices: a        mobile station (mobile phone), smartphone, personal digital        assistant (PDA), handset, device using a wireless modem (alarm        or measurement device, etc.), laptop and/or touch screen        computer, tablet, game console, notebook, and multimedia device.        It should be appreciated that a user device may also be a nearly        exclusive uplink only device, of which an example is a camera or        video camera loading images or video clips to a network, or a        nearly exclusive downlink only device, such as a portable video        player. It should be appreciated that a device may be regarded        as an apparatus or as an assembly of more than one apparatus,        whether functionally in cooperation with each other or        functionally independently of each other but in a same device        housing.    -   embodiments suitable to be implemented as software code or        portions of it and being run using a processor or processing        function are software code independent and can be specified        using any known or future developed programming language, such        as a high-level programming language, such as objective-C, C,        C++, C#, Java, etc., or a low-level programming language, such        as a machine language, or an assembler.    -   implementation of embodiments is hardware independent and may be        implemented using any known or future developed hardware        technology or any hybrids of these, such as a microprocessor or        CPU (Central Processing Unit), MOS (Metal Oxide Semiconductor),        CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar        CMOS), ECL (Emitter Coupled Logic), and/or TTL        (Transistor-Transistor Logic).    -   embodiments may be implemented as individual devices,        apparatuses, units, means or functions, or in a distributed        fashion, for example, one or more processors or processing        functions may be used or shared in the processing, or one or        more processing sections or processing portions may be used and        shared in the processing, wherein one physical processor or more        than one physical processor may be used for implementing one or        more processing portions dedicated to specific processing as        described,    -   an apparatus may be implemented by a semiconductor chip, a        chipset, or a (hardware) module comprising such chip or chipset;    -   embodiments may also be implemented as any combination of        hardware and software, such as ASIC (Application Specific IC        (Integrated Circuit)) components, FPGA (Field-programmable Gate        Arrays) or CPLD (Complex Programmable Logic Device) components        or DSP (Digital Signal Processor) components.    -   embodiments may also be implemented as computer program        products, comprising a computer usable medium having a computer        readable program code embodied therein, the computer readable        program code adapted to execute a process as described in        embodiments, wherein the computer usable medium may be a        non-transitory medium.

Although the present invention has been described herein before withreference to particular embodiments thereof, the present invention isnot limited thereto and various modifications can be made thereto.

For example, while in the above described examples of embodiments an MMEis used as an example for the virtualized network function to bede-instantiated, the invention is not limited thereto. For example,other network entities such as, SGSN, GGSN, SGW, PGW, SGW-C, SGW-U,PGW-C, PGW-U etc., or a RAN element like an eNB may be used as examplesof a virtualized network function to which the described examples ofembodiments are applicable. As indicated above, examples of embodimentsof the invention are also applicable for other network systems, such asan IMS based system, where elements like a P-CSCF, IBCF, BGCF, MGCF etcmay be instantiated as virtualized network functions where examples ofembodiments of the invention are applicable.

The invention claimed is:
 1. An apparatus, comprising: at least oneprocessor; and at least one memory for storing instructions to beexecuted by the processor; wherein the at least one memory and theinstructions are configured to, with the at least one processor, causethe apparatus at least to: host subscription data of communicationelements of a communication network attached to virtualized networkfunctions on the basis of a stored indication, store an indication forthe virtualized network functions indicating whether the virtualizednetwork functions are de-instantiated, forming the stored indication,receive and process a message directed to a virtualized network functionproviding services related to the communication network, check whetherthe virtualized network function is indicated to be still instantiatedor not, and in case the result of the check is that the virtualizednetwork function is de-instantiated, conduct a simulation processsimulating a function of the virtualized network function beingde-instantiated and reply to the received message on behalf of thede-instantiated virtualized network function by the simulation process,wherein the apparatus is implemented by a communication network controlelement or communication network control function acting as anintermediate network element or intermediate network function forvirtualized network functions, and wherein the virtualized networkfunction is related to a communication network control function of thecommunication network.
 2. The apparatus according to claim 1, whereinthe at least one memory and the instructions are further configured to,with the at least one processor, cause the apparatus at least: in casethe result of the check is that the virtualized network function isstill instantiated, forward the message to the virtualized networkfunction.
 3. The apparatus according to claim 1, wherein the simulationprocess comprises replying to the received message on behalf of thede-instantiated virtualized network function on the basis of thesubscription data.
 4. A method, comprising: hosting subscription data ofcommunication elements of a communication network attached tovirtualized network functions; storing an indication for the virtualizednetwork functions indicating whether the virtualized network functionsare de-instantiated; receiving and processing a message directed to avirtualized network function providing services related to thecommunication network; checking whether the virtualized network functionis indicated to be still instantiated or not; and in case the result ofthe checking is that the virtualized network function isde-instantiated, conducting a simulation process simulating a functionof the virtualized network function being de-instantiated and replyingto the received message on behalf of the de-instantiated virtualizednetwork function by means of the simulation process, wherein the methodis implemented by a communication network control element orcommunication network control function acting as an intermediate networkelement or intermediate network function for virtualized networkfunctions, and wherein the virtualized network function is related to acommunication network control function of the communication network. 5.A non-transitory computer-readable medium storing instructions that,when executed by a processing device, to perform: hosting subscriptiondata of communication elements of a communication network attached tovirtualized network functions on the basis of a stored indication;storing an indication for the virtualized network functions indicatingwhether the virtualized network functions are de-instantiated; receivingand processing a message directed to a virtualized network functionproviding services related to a communication network; checking, on thebasis of the stored indication, whether the virtualized network functionis indicated to be still instantiated or not; and in case the result ofthe check is that the virtualized network function is de-instantiated,conducting a simulation process simulating a function of the virtualizednetwork function being de-instantiated and replying to the receivedmessage on behalf of the de-instantiated virtualized network function bymeans of the simulation process, wherein the processing device isimplemented by a communication network control element or communicationnetwork control function acting as an intermediate network element orintermediate network function for virtualized network functions, andwherein the virtualized network function is related to a communicationnetwork control function of the communication network.
 6. The methodaccording to claim 4, further comprising: in case the result of thechecking is that the virtualized network function is still instantiated,forwarding the message to the virtualized network function.
 7. Themethod according to claim 4, wherein the conducting of the simulationprocess comprises replying to the received message on behalf of thede-instantiated virtualized network function on the basis of thesubscription data.
 8. The method according to claim 4, wherein thevirtualized network function is related to a communication networkcontrol function of the communication network.